Screening for Latent Tuberculosis Infection

Abstract

The US Preventive Services Task Force (USPSTF) has recommended screening of adults at increased risk for latent tuberculosis (TB) infection (LTBI). 1 This recommendation (B statement) is based on an evidence review 2 that found that available tests-in particular, the tuberculin skin test and interferon-γ release assays-were sufficiently accurate to identify persons with LTBI and that TB preventive treatment (TPT) regimens now recommended in the US 3 should provide moderate net benefit 1 to persons identified from screening. The USPSTF advised following the recommendations for testing in persons who have immunosuppression made by the American Thoracic Society and Centers for Disease Control and Prevention 2017 4 and recommendations for TPT made by the Centers for Disease Control and Prevention in 2020. 3 The USPSTF noted that this recommendation is for adults not included in other recommendations 3,4 for LTBI testing and treatment, such as persons living with HIV, persons about to receive a solid-organ transplantation or tumor necrosis factor-α inhibitors, or other groups at increased risk because of immune suppression. The task force also noted that this recommendation is not for contacts of persons with a recent diagnosis of active TB disease, who are generally investigated by public health services. Hence, these recommendations are focused on persons who are otherwise healthy but have increased likelihood (risk) of having TB infection. Although this includes some US-born persons, the vast majority of persons who will be affected by this recommendation are individuals who immigrated to the US from countries where TB incidence is much higher. On the basis of estimates of the prevalence of LTBI among persons in the US who were born outside the US, 5 this represents a very substantial increase from the number of persons now screened.Before starting screening, a reminder is needed. The USPSTF also recommends that to achieve the benefit of screening, it is important that persons who screen positive for LTBI receive follow-up and treatment 1 ; if TPT is not completed, then there will be no benefit of screening. Hence, a decision to implement screening for LTBI in any setting or for any population must include a commitment to ensure adequate follow-up of those with positive test results. 6 This includes medical and radiographic evaluation to exclude TB disease, offering TPT to all those who are eligible, and then education and counseling plus subsequent close follow-up of those who accept TPT, to ensure adherence as well as to detect and manage any adverse effects. Substantial time and resources are needed to ensure that care is well organized for all steps in the cascade to minimize losses, or a screening program will have far less benefit than expected. 6 Numerous studies have shown that there are substantial losses in the cascade of LTBI care, at the steps of initial identification of candidates for screening (testing), medical evaluation, and offering TPT, as well as acceptance and completion of TPT by individuals,...

Losses in the Care Cascade for Latent Tuberculosis Infection in the Tracing Contact Studies

“…In the last two cascade stages, 50.5% of the infected patients were lost (30.6% before and 19.9% after starting treatment). The fact that most losses occurred before starting treatment suggests that the health service prescription of treatment needs to be improved, as concluded in other studies evaluating the LTBI care cascade [5,13].…”

“…Our results, pointing to important losses in the LTBI care cascade, suggest a need for patient education, incentives, home visits, and treatment monitoring. The control of LTBI, as key to achieving the goal of ultimately eliminating TB, also requires the implication of the entire health system, but especially of TB clinics [9] and primary care physicians [5]. The inclusion of LTBI data in computerized medical record systems, with primary care protocols and alerts already existing for the control of chronic pathologies, could greatly assist in LTBI monitoring and control.…”

“…We used an LTBI care cascade model, as previously published (12), consisting of the following stages: (1) the identification of close pulmonary TB contacts (reference population); (2) initial screening for LTBI; (3) medical examination including IGRA, TST, and/or X-ray evaluation; (4) recommendation to receive treatment; (5) acceptance and initiation of treatment; and (6) treatment compliance (defined as 80% of the prescribed medication).…”

“…The control of LTBI encompasses multiple stages, starting with identifying a population for testing-using the tuberculin skin test (TST) and/or the interferon gamma release assay (IGRA)-and ending with treatment completion [2][3][4]. Several studies have indicated Pathogens 2023, 12, 1403 2 of 9 that significant losses occur at all stages of the LTBI cascade, but especially in the early stages and with treatment prescription and adherence to treatment [5].…”